APOLIPOPROTEIN-E POLYMORPHISM IS ASSOCIATED WITH SEGMENT-SPECIFIC EXTRACRANIAL CAROTID-ARTERY INTIMA-MEDIA THICKENING

Background and Purpose Apolipoprotein E (apoE) polymorphism affects pl asma cholesterol and may influence risk of atherosclerosis. We investi gated the association of apoE with carotid artery wall thickening (an index of atherosclerosis) in individuals with and without coronary art ery disease (CAD). Methods ApoE phenotypes were resolved in 260 indivi duals equally represented by angiographically determined CAD case subj ects and disease-free control subjects. Carotid artery intima-media th ickening (IMT) was evaluated by B-mode ultrasound. Associations of apo E (E2, E3, or E4) with risk factors and IMT were evaluated in general linear models adjusted for age, sex, and CAD status with and without o ther traditional risk factors. Results Total cholesterol (TC) and LDL cholesterol were associated with apoE isoforms. Mean TC and LDL choles terol were lower in E2 (n=33) carriers than E3 (n=155) and E4 (n=66) c arriers (each P<.001). IMT also varied by apoE. E2 carriers had less c ommon carotid IMT than E3 and E4 carriers (P<.01), while internal caro tid IMT was less in E2 and E3 carriers than in E4 carriers (P<.02). Bi furcation IMT was not associated with apoE (P=.24). ApoE polymorphism remained associated with common (P<.01) and internal (P<.04) IMT, and the association of apoE with mean IMT of all sites reached significanc e (P<.04) after adjustment for age, sex, CAD status, TC, LDL cholester ol, HDL cholesterol, triglycerides, diabetes, hypertension, and smokin g. Conclusions ApoE polymorphism is associated with segment-specific c arotid IMT. The association of apoE with carotid IMT was statistically independent of apoE-associated variation in LDL cholesterol levels.